Electric alarm device



March 19, 1957 M. COLETTE ELECTRIC ALARM DEVICE Filed Sept. 3. 1952 INVENTOR. MICHAEL COLETTE ATTOR/VEX United States Patent O ELECTRIC ALARM DEVICE Michael Colette, Detroit, Mich., assignor, by mesne a ssignments, to Hebel Enterprise Corporation, Detroit, Mich., a corporation of Michigan Application September 3, 1952, Serial No. 307,672

1 Claim. (Cl. 340-220) This invention relates to signal devices and more particularly to an improved electric fire alarm and/or an alarm indicating presence of heating gas in the air in dangerous proportions.

One of the objects of the present invention is to provide an improved signal device of the foregoing nature which gives audible and/ or visible alarm when the ambient temperature rises beyond a predetermined limit and/or when heating gas is leaking into the enclosure because of loose connections or opened gas jets.

Another object of the present invention is to provide an improved electric device of the nature specified in the preceding paragraph, which device is so constructed that it is not under electric pressure and does not have current circulating therethrough until alarm is sounded, thereby adding to the safety and economy of the operation of the device, and which switches itself off automatically when v the condition that excited it ceases.

A further object of the present invention is to provide an improved fire and/ or gas alarm, installation of which is exceedingly simple and easy and involves merely plugging the alarm into a common lighting circuit, such as done in the case of a radio, toaster, iron or a similar home appliance. v v

A still further object of the present invention is to provide an improved alarm including an electric vibrator having an armature or vibrator piece of an improved con- 7 struction.

A still further object of the present invention is to provide an improved gas alarm including an electric switch, means being provided to eliminate sparking at the contact points of said switch and thus to eliminate the danger of igniting the explosive gas-and-air mixture that may be formed within the enclosure in which the alarm is in stalled.

Further objects and advantages of this invention will be apparent from the following description and appended claim, reference being had to the accompanying drawings forming a part of this specification, wherein like reference characters designate corresponding parts in the several views.

Fig. 1 is a perspective view showing my improved alarm as it appears when installed.

Fig. 2 is an elevational view of the device of Fig. l with the cover thereof removed, and showing the construction thereof.

Fig. 3 is an electrical diagram of my improved device.

Fig. 4 is an elevational view, partly in section, showing the construction of the vibrator, said view being taken in the direction of the arrows on the plane passing through line 44 of Fig. 2.

Fig. 5 is a fragmentary view similar in part to Fig. 4 but showing on a larger scale the lower portion of the vibrator.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments 2,786,195 Patented Mar. 19,

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and of being practiced or carried out in various ways. Also it is to be understood that the phraseology and terminology employed here is for the purpose of description and not of limitation.

It will be understood that the term gas as used herein refers to illuminating, heating and similar gases or mixture of gases, admixture of which to the air while occurring in practice is undesirable and dangerous because of the possibility of poisoning or explosion.

In accordance with the invention I provide a signal device adapted to be inserted into an electric circuit and including an electric vibrator inherently advantageous when used in an illuminating circuit with alternating current and not requiring circuit interrupter, and a switch including a bi-metallic element and responsive to ambient temperatures. The switch is adapted normally to maintain the circuit open and to close the same when ambient temperature or temperature of the surrounding air reaches a predetermined limit. A device of this nature serves as a fire alarm or a device giving a signal of rise of the ambient temperature beyond a predetermined limit. In addition, by attaching to the bi-rnetallic element a piece of material adapted to be heated by the action of the gas, such as sponge platinum, I provide a device giving a signal when gas content in the air reaches a predetermined limit. The substance such as sponge platinum has a property of becoming heated when it comes in contact with such gases. When so heated in my device, the substance heats the bi-metallic element and causes the same to close the circuit and to give an alarm as in the case of a fire. 3

It should be understood that for the purpose of heat ing the bi-metallic element the gas content in the air need not be exceedingly high. It is well known that similar substances have been used as ignitors for the heating gas in gas stoves and when contacted by a stream of gas, they heat to such a high temperature as to ignite the gas. No such high temperature is required in the present application.

In order to prevent sparking at the contacts of the switch, I connect a condenser or capacitator across theterminals of the switch to eliminate sparking and possibility of igniting by the spark the explosive mixture of gas and air that may be formed within the enclosure. Also the contact points may be sealed.

Referring to the drawing, there is shown therein, by way of example, one embodiment of the present invention. The device illustrated in the drawing comprises a box having a back plate 10 having an upper extension 10a and a lower extension 10b, on which a front cover 11 covering said plate 10 is slipped on. The lower extension 10b has provided in its bottom an aperture 12 intended to admit air and radiation to heat the bi-metallic element of the switch. On the plate 10 there is secured in any suitable manner a vibrator 15 including a winding or coil 16 and a laminated type electro-magnet 17. A vibrator piece 18 is operatively mounted within the magnetic field created by the magnet 17. The vibrator piece comprises a piece of thin sheet phosphorus bronze 18a secured as indicated at 19, with a steel strip 20 wrapped around the free edge of the piece 18a and secured thereto by being pressed thereon. The piece 18a is non-magnetic and non-corroding and is easily responsive to the action of the steel piece 20 acting upon the magnet Rapid vibration of the vibrator piece 18 causes the piece 20 to hit the end of the central lamination 17a and the bottom of the back plate 10 and thus to produce a buzzing sound audible at considerable distances. Thus the back plate 10 serves also as a sounding board. The device is intended to be plugged into a usual lighting circuit carrying alternating current, such plugging being eflected with the aid of a plug 21.

Means are provided to keep the circuit through the coil 16 normally interrupted and to close the same only temperature.

when the temperature acting on the bi-metallic element 25 rises beyond a predetermined limit. In the present embodiment of the invention said means are exemplified by a switch which comprises a bimetallic element 26 of a suitable character mounted as indicated at 27 and adapted toclose the circuit at a contact point 28. A condenser or capacitor 29 is operatively connected across the contact points of theswi-tch to eliminate sparking thereat, as

mentioned.

The bi-metallic element has a well known property peculiar to such elements of bending as the temperature changes. In the present embodiment, as the temperature increases, the bi-metallic strip bends and coming in contact with the point 28 closes the circuit. The degree of bending of the bi-metallic element 26 depends uponthe I prefer to construct my device in such a manner that the bi-rnetallic element 26 closes the circuit when heated to approximately 150 F, since such temperature does not normally occur in enclosures unless some heat-producing device therein is overheated or unless uncontrolled combustion commences.

My fire alarm constructed as above described may be used in homes for detecting overheating of furnaces or actual fires and be installed in basements, attics, kitchens or other rooms of the house. It may be also used in industrial field both as a fire alarm and as a temperature alarm, in the latter case giving a signal when a certain device or medium became heated above predetermined temperature.

Means are provided whereby my improved fire alarm operates also as a gas alarm detecting undesirably large or dangerous content of heating gas in the air. With the increasing use of gas for heating homes, many serious explosions of homes occur yearly, which explosions could have been prevented and lives that are usually lost in such an occurance be 'saved if a warning signal were given as soon as the dangerous condition occurred.

In the present embodiment of the invention such means are exemplified by a piece or a layer of substance such as sponge platinum which has a property of becoming heated when in contact with heating gas or hydrogen. A piece of such substance indicated by the numeral 30 is secured or otherwise applied, such as by spraying, to the bimetallic element 26. I prefer to secure such piece on the side of the bi-metallic element exposed toward the controlled space and to mount the bimetallic piece in such a manner that the metal of high heat conductivity is one to which the piece 30 is attached.

In operation, when the proportion of gas in the air reaches a value capable of heating the substance of the piece 30, the heat from said piece is transferred to the bimetallic piece 26 causing the same to close the electric contact and thus to complete the circuit. In consequence thereof the vibrator piece produces and audible sound and alarm indicating presence of gas in the air in a dangerously large proportion. Provision of the condenser 29 substantially eliminates sparking at the contact points and therefore igniting the explosive mixture that may be formed within the enclosure by the time the alarm sounds. In particularly critical installations, the contact points may also be sealed.

By virtue of the above described construction, the objects of the present invention listed above and numerous additional advantages are attained.

I claim:

A unitary self-contained signal device adapted to sound an alarm either when the ambient temperature exceeds a preselected degree or when hydrogen containing gas enters said signal device, the latter being constructed and arranged for use in a building supplied with alternating electric current and comprising a housing having a back plate, a front cover detachably connected thereto and means for attaching said housing to said building, an eleotro-magnetic vibrator mounted on said back plate with the armature in position to strike the core of the magnet and the back plate alternately when the coil of the magnet is energized, a normally open heat responsive bi-metallic element mounted on said back plate, an electric circuit containing said coil and said bi-metallic element in series so that when the ambient temperature exceeds a pre selected degree the bi-metallic element will close the circuit through said coil, a piece of sponge platinum secured to said bi-metallic element to be heated by the action of hydrogen containing gas and transfer its heat to said himetallic element causing the latter to close the aforesaid circuit, and an electric extension cord forming a part of said circuit for energizing the same, said cord extending through an opening in said housing to permit plugging the same into a conventional electric receptacle in said building remote from the place where the housing is attached to the building.

References Cited in the file of this patent UNITED STATES PATENTS Nuccio Sept, 

